Functionalizing cellulosic and lignocellulosic materials

ABSTRACT

Irradiated lignocellulosic or cellulosic materials are provided which contain carboxylic acid groups and/or other functional groups not present in a naturally occurring cellulosic or lignocellulosic material from which the irradiated material was obtained

RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application Ser.Nos. 61/049,391, 61/049,395, and 61/049,394, all of which were filedApr. 30, 2008, and to 61/073,432 and 61/073,436, both of which werefiled Jun. 18, 2008. The complete disclosure of each of theseprovisional applications is hereby incorporated by reference herein.

TECHNICAL FIELD

This invention relates to methods of functionalizing cellulosic andlignocellulosic materials, e.g., with carboxylic acid groups, and theresulting functionalized materials.

BACKGROUND

Cellulosic and lignocellulosic materials, such as papers, wood products,and cellulosic textiles, generally contain relatively few carboxylicacid groups.

SUMMARY

The invention is based, in part, on the discovery that by irradiatingfibrous materials at appropriate levels, the functional groups of atleast the cellulosic portions of the materials can be altered. Ionizingradiation and any applied quenching step can also be used to control thefunctionalization of the cellulosic or lignocellulosic material, i.e.,the functional groups that are present on or within the material.

In one aspect, the invention features a method comprising irradiating alignocellulosic or cellulosic material to provide an irradiatedlignocellulosic or cellulosic material containing a larger number ofcarboxylic acid groups than the cellulosic or lignocellulosic materialprior to irradiation. The number of carboxylic acid groups is determinedby titration.

Some implementations include one or more of the following features.

The treated material can also include functional groups selected fromthe group consisting of aldehyde groups, nitroso groups, nitrile groups,nitro groups, ketone groups, amino groups, alkyl amino groups, alkylgroups, chloroalkyl groups, chlorofluoroalkyl groups, and enol groups.

In some implementations, the irradiated material may include a pluralityof saccharide units arranged in a molecular chain, and from about 1 outof every 5 to about 1 out of every 1500 saccharide units comprises anitroso, nitro, or nitrile group, e.g., from about 1 out of every 10 toabout 1 out of every 1000 saccharide units of each chain comprises anitroso, nitro, or nitrile group, or from about 1 out of every 35 toabout 1 out of every 750 saccharide units of each chain comprises anitroso, nitro, or nitrile group. In some cases the irradiated materialcomprises a mixture of nitrile groups and carboxylic acid groups.

In some embodiments, the saccharide units can include substantially onlya single type of group, such as a carboxylic acid group, a nitrilegroup, a nitroso group or a nitro group.

The naturally occurring cellulosic or lignocellulosic fibrous materialcan, for example, be selected from the group consisting of wood, paper,and textile fibers. In some cases, the lignocellulosic or cellulosicmaterial comprises a fibrous material.

The irradiated material may include a plurality of saccharide unitsarranged in a molecular chain, and from about 1 out of every 2 to about1 out of every 250 saccharide units can include a carboxylic acid group,or an ester or salt thereof. The irradiated material may include aplurality of such molecular chains. In some cases from about 1 out ofevery 5 to about 1 out of every 250 saccharide units of each chaincomprises a carboxylic acid group, or an ester or salt thereof, e.g.,from about 1 out of every 8 to about 1 out of every 100 saccharide unitsof each chain comprises a carboxylic acid group, or an ester or saltthereof, or from about 1 out of every 10 to about 1 out of every 50saccharide units of each chain comprise a carboxylic acid group, or anester or salt thereof. The saccharide units can, for example, comprise 5or 6 carbon saccharide units, and each chain can have between about 10and about 200 saccharide units, e.g., between about 10 and about 100 orbetween about 10 and about 50. In some embodiments each chain compriseshemicellulose or cellulose.

In some cases the average molecular weight of the irradiated materialrelative to PEG standards is from about 1,000 to about 1,000,000,wherein the molecular weight is determined using GPC, utilizing asaturated solution (8.4% by weight) of lithium chloride (LiCl) indimethyl acetamide (DMAc) as the mobile phase.

Irradiating may be performed using a device that is disposed in a vault.

In another aspect, the invention features a method comprising surfacetreating with a coating or a dye a cellulosic or lignocellulosicmaterial that has been irradiated to functionalize the material withcarboxylic acid groups not present in a naturally occurring cellulosicor lignocellulosic material from which the irradiated material wasobtained.

In another aspect, the invention features a cellulosic orlignocellulosic material that includes a significantly larger number ofcarboxylic acid groups than in naturally occurring versions of thecellulosic or lignocellulosic material.

In yet another aspect, the invention features a method comprisinggrafting a material onto grafting sites of a cellulosic orlignocellulosic material that has been irradiated to provide afunctionalized cellulosic material having a plurality of grafting sites.

In some cases, the grafting material comprises a reactive dye.

The irradiated material can be, for example, paper, a textile material,wood, or a product containing wood. Any of these products can be coatedor uncoated. For example, in the case of a textile the textile can havea sizing coating such as starch or a starch derivative.

Textile materials can include, for example, yarns or fabrics. In somecases, the α-cellulose content of the material can be less than about80%. The fibrous cellulosic materials can be selected from the groupconsisting of flax, hemp, jute, abaca, sisal, banana fiber, coconutfiber, wheat straw, LF, ramie, bamboo fibers, cuprammonium cellulose,regenerated wood cellulose, lyocell, cellulose acetate, and blendsthereof. Other useful fibers include fibers made from corn or otherstarch- or protein-containing plant or vegetable materials such as soy,milk-based fibers, and chitin fibers made from, e.g., shrimp or crabshells. The fibrous cellulosic materials can have a lignin content of atleast 2%. The fibrous cellulosic materials can be irradiated prior to,during, or after being spun, woven, knitted, or entangled. Irradiationof textile materials is discussed in U.S. Provisional Application Nos.61/049,394 and 61/073,436, the full disclosures of which areincorporated herein by reference.

The full disclosures of each of the following U.S. patent applications,which are being filed concurrently herewith, are hereby incorporated byreference herein: Attorney Docket Nos. 08995-0062001, 08895-0063001,08895-0070001, 08895-0073001, 08895-0075001, 08895-0076001,08895-0085001, 08895-0086001, and 08895-0096001.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Although methods and materialssimilar or equivalent to those described herein can be used in thepractice or testing of the present invention, suitable methods andmaterials are described below. All mentioned publications, patentapplications, patents, and other references are incorporated herein byreference in their entirety. In case of conflict, the presentspecification, including definitions, will control. In addition, thematerials, methods and examples are illustrative only and not intendedto be limiting.

Other features and advantages of the invention will be apparent from thefollowing detailed description, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram that illustrates changing a molecular and/or asupramolecular structure of a fibrous material.

FIG. 2 is a perspective, cut-away view of a gamma irradiator housed in aconcrete vault.

FIG. 3 is an enlarged perspective view of region, R, of FIG. 2.

FIG. 4 is a schematic diagram of a DC accelerator.

FIG. 5 is an infrared spectrum of Kraft board paper sheared on a rotaryknife cutter.

FIG. 6 is an infrared spectrum of the Kraft paper of FIG. 5 afterirradiation with 100 Mrad of gamma radiation.

FIGS. 6A-6I are ¹H-NMR spectra of samples P132, P132-10, P132-100, P-1e,P-5e, P-10e, P-30e, P-70e, and P-10e in Example 4. FIG. 6J is acomparison of the exchangeable proton at ˜16 ppm from FIGS. 6A-6I. FIG.6K is a ¹³C-NMR of sample P-100e. FIGS. 6L-6M are ¹³C-NMR of sampleP-100e with a delay time of 10 seconds.

FIG. 6N is a ¹H-NMR at a concentration of 10% wt./wt. of sample P-100e.

DETAILED DESCRIPTION

As discussed above, the invention is based, in part, on the discoverythat by irradiating fibrous materials, i.e., cellulosic andlignocellulosic materials, at appropriate levels, the molecularstructure of at least a cellulosic portion of the fibrous material canbe changed.

Various cellulosic and lignocellulosic materials, their uses, andapplications have been described in U.S. Pat. Nos. 7,307,108, 7,074,918,6,448,307, 6,258,876, 6,207,729, 5,973,035 and 5,952,105; and in variouspatent applications, including “FIBROUS MATERIALS AND COMPOSITES,”PCT/US2006/010648, filed on Mar. 23, 2006, and “FIBROUS MATERIALS ANDCOMPOSITES,” U.S. Patent Application Publication No. 2007/0045456. Theaforementioned documents are all incorporated by reference herein intheir entireties.

Ionizing radiation can be used to control the functionalization of thefibrous material, i.e., the functional groups that are present on orwithin the material, which can increase solubility and/or dispersibilityduring pulping, and can favorably affect the surface properties of a thematerial, e.g., the receptivity of the surface to coatings, inks anddyes and the available grafting sites.

Irradiating can be conducted under conditions that favorably alter thefunctional groups present in the material.

In some embodiments, after irradiation from about 1 out of every 2 toabout 1 out of every 250 saccharide units includes a carboxylic acidgroup, or an ester or salt thereof, whereas the native or unprocessedbase material can have less than 1 carboxylic acid group per 300saccharide units. In other embodiments, from about 1 out of every 5 toabout 1 out of every 250 saccharide units, e.g., 1 out of every 8 toabout 1 out of every 100 units or from 1 out of 10 to about 1 out of 50units includes a carboxylic acid group, or an ester or salt thereof.

In some embodiments, in the irradiated material from about 1 out ofevery 5 to about 1 out of every 1500 saccharide units includes a nitrilegroup, a nitroso groups or a nitro group. In other embodiments, fromabout 1 out of every 10 to about 1 out of every 1000 saccharide units,e.g., 1 out of every 25 to about 1 out of every 1000 units or from 1 outof 35 to about 1 out of 750 units includes a nitrile group, a nitrosogroups or a nitro group.

In some embodiments, the saccharide units include mixtures of carboxylicacid groups, nitrile groups, nitroso groups and nitro groups. Mixedgroups can enhance the solubility of a cellulosic or lignocellulosicmaterial.

If desired, irradiation may be performed multiple times to achieve agiven final dose, e.g., delivering a dose of 1 MRad repeated 10 times,to provide a final dose of 10 MRad. This may prevent overheating of theirradiated material, particularly if the material is cooled betweendoses.

Irradiating to Affect Material Functional Groups

After treatment with one or more ionizing radiations, such as photonicradiation (e.g., X-rays or gamma-rays), e-beam radiation or irradiationwith particles heavier than electrons that are positively or negativelycharged (e.g., protons or carbon ions), any of thecarbohydrate-containing materials or mixtures described herein becomeionized; that is, they include radicals at levels that are detectable,for example, with an electron spin resonance spectrometer. Afterionization, any material that has been ionized can be quenched to reducethe level of radicals in the ionized material, e.g., such that theradicals are no longer detectable with the electron spin resonancespectrometer. For example, the radicals can be quenched by theapplication of sufficient pressure to the ionized material and/or bycontacting the ionized material with a fluid, such as a gas or liquid,that reacts with (quenches) the radicals.

Various gases, for example nitrogen or oxygen, or liquids, can be usedto at least aid in the quenching of the radicals and to functionalizethe ionized material with desired functional groups. Thus, irradiationfollowed by quenching can be used to provide a material with desiredfunctional groups, including, for example, one or more of the following:aldehyde groups, enol groups, nitroso groups, nitrile groups, nitrogroups, ketone groups, amino groups, alkyl amino groups, alkyl groups,chloroalkyl groups, chlorofluoroalkyl groups, and/or carboxylic acidgroups.

These groups can in some instances increase the hydrophilicity of theregion of the material where they are present. In some implementations,for example, a paper web is irradiated and quenched, before or afterprocessing steps such as coating and calendering, to affect thefunctionality within and/or at the surface of the paper and therebyaffect the ink receptivity and other properties of the paper. In otherimplementations, the paper feedstock is irradiated with a relativelyhigh dose of ionizing radiation, to facilitate pulping, and then laterquenched to improve the stability of the ionized material in the pulp.

FIG. 1 illustrates changing a molecular and/or a supramolecularstructure of fibrous material, such as paper feedstock, paper precursor(e.g., a wet paper web), or paper, by pretreating the fibrous materialwith ionizing radiation, such as with electrons or ions of sufficientenergy to ionize the material, to provide a first level of radicals. Asshown in FIG. 1, if the ionized material remains in the atmosphere, itwill be oxidized, e.g., to an extent that carboxylic acid groups aregenerated by reaction with the atmospheric oxygen. In some instances,with some materials, such oxidation is desired, because it can aid infurther breakdown in molecular weight of the carbohydrate-containingmaterial (for example, if irradiation is being used to facilitatepulping). However, since the radicals can “live” for some time afterirradiation, e.g., longer than 1 day, 5 days, 30 days, 3 months, 6months, or even longer than 1 year, material properties can continue tochange over time, which in some instances can be undesirable.

Detecting radicals in irradiated samples by electron spin resonancespectroscopy and radical lifetimes in such samples is discussed inBartolotta et al., Physics in Medicine and Biology, 46 (2001), 461-471and in Bartolotta et al., Radiation Protection Dosimetry, Vol. 84, Nos.1-4, pp. 293-296 (1999). The ionized material can be quenched tofunctionalize and/or to stabilize the ionized material.

In some embodiments, quenching includes application of pressure to theionized material, such as by mechanically deforming the material, e.g.,directly mechanically compressing the material in one, two, or threedimensions, or applying pressure to fluid in which the material isimmersed, e.g., isostatic pressing. In the case of paper that has beenionized, pressure may be applied, e.g., by passing the paper through anip. In such instances, the deformation of the material itself bringsradicals, which are often trapped in crystalline domains, into proximityclose enough for the radicals to recombine, or react with another group.In some instances, pressure is applied together with application ofheat, e.g. a quantity of heat sufficient to elevate the temperature ofthe material to above a melting point or softening point of a componentof the ionized material, such as lignin, cellulose or hemicellulose.Heat can improve molecular mobility in the material, which can aid inquenching of radicals. When pressure is utilized to quench, the pressurecan be greater than about 1000 psi, such as greater than about 1250 psi,1450 psi, 3625 psi, 5075 psi, 7250 psi, 10000 psi, or even greater than15000 psi.

In some embodiments, quenching includes contacting the ionized materialwith fluid, such as liquid or gas, e.g., a gas capable of reacting withthe radicals, such as acetylene or a mixture of acetylene in nitrogen,ethylene, chlorinated ethylenes or chlorofluoroethylenes, propylene ormixtures of these gases. In other particular embodiments, quenchingincludes contacting the ionized material with liquid, e.g., a liquidsoluble in, or at least capable of penetrating into, the ionizedmaterial and reacting with the radicals, such as a diene, such as1,5-cyclooctadiene. In some specific embodiments, the quenching includescontacting the ionized material with an antioxidant, such as Vitamin E.If desired, the material can include an antioxidant dispersed therein,and quenching can come from contacting the antioxidant dispersed in thematerial with the radicals.

Other methods for quenching are possible. For example, any method forquenching radicals in polymeric materials described in Muratoglu et al.,U.S. Patent Publication No. 2008/0067724 and Muratoglu et al., U.S. Pat.No. 7,166,650, the disclosures of which are incorporated herein byreference in their entireties, can be utilized for quenching any ionizedmaterial described herein. Furthermore, any quenching agent (describedas a “sensitizing agent” in the above-noted Muratoglu disclosures)and/or any antioxidant described in either Muratoglu reference, can beutilized to quench any ionized material.

Functionalization can be enhanced by utilizing heavy charged ions, suchas any of the heavier ions described herein. For example, if it isdesired to enhance oxidation, charged oxygen ions can be utilized forthe irradiation. If nitrogen functional groups are desired, nitrogenions or any ion that includes nitrogen can be utilized. Likewise, ifsulfur or phosphorus groups are desired, sulfur or phosphorus ions canbe used in the irradiation.

In some embodiments, after quenching, any of the quenched ionizedmaterials described herein can be further treated with one or morefurther doses of radiation, such as ionizing or non-ionizing radiation,sonication, pyrolysis, and oxidation for additional molecular and/orsupramolecular structure change.

In some embodiments, the fibrous material is irradiated under a blanketof inert gas, e.g., helium or argon, prior to quenching.

The location of the functional groups can be controlled, e.g., byselecting a particular type and dose of ionizing particles. For example,gamma radiation tends to affect the functionality of molecules withinpaper, while electron beam radiation tends to preferentially affect thefunctionality of molecules at the surface.

In some cases, functionalization of the material can occursimultaneously with irradiation, rather than as a result of a separatequenching step. In this case, the type of functional groups and degreeof oxidation can be affected in various ways, for example by controllingthe gas blanketing the material to be irradiated, through which theirradiating beam passes. Suitable gases include nitrogen, oxygen, air,ozone, nitrogen dioxide, sulfur dioxide and chlorine.

In some embodiments, functionalization results in formation of enolgroups in the fibrous material. When the fibrous material is paper, thiscan enhance receptivity of the paper to inks, adhesives, coatings, andthe like, and can provide grafting sites. Enol groups can help breakdown molecular weight, especially in the presence of added base or acid.Thus, the presence of such groups can assist with pulping. In thefinished paper product, generally the pH is close enough to neutral thatthese groups will not cause a deleterious decrease in molecular weight.

In some implementations, the material is irradiated and quenched beforeor after processing steps such as dyeing and sizing, to affect thefunctionality within and/or at the surface of the material and therebyaffect properties of the material such as the receptivity of thematerial surface to sizes, dyes, coatings, and the like, and theadherence of sizes, dyes, coatings, and the like to the material.

Functionalization can also favorably change various textile properties.For example, functionalization can change the charge density of atextile material. In some implementations, functionalization can enhancemoisture regain (as measured according to ASTM D2495), e.g., themoisture regain of the textile can be increased by at least 5%, 10%,25%, 50%, 100%, 250%, or 500% relative to untreated cellulosic material.This increase in moisture regain can be significant in enhancing wickingaction, bend recovery, and resistance to static electricity.Functionalization can also enhance the work recovery of cellulosicfibers (as measured according to ASTM D1774-94), e.g., by at least 5%,10%, 25%, 50%, 100%, 250%, or 500% relative to untreated cellulosicmaterial. The work recovery of the fibers can affect the wrinkleresistance of a fabric formed from the cellulosic material, with anincrease in work recovery generally enhancing wrinkle resistance.Functionalization can also increase the decomposition temperature of thecellulosic material or a textile formed from the cellulosic material,e.g., by at least 3, 5, 10 or 25 degrees C. The decompositiontemperature is measured by TGA in an air atmosphere, for example usingIPC-TM-650 of the Institute for Interconnecting and Packaging ElectronicCircuits, which references ASTM D 618 and D 3850.

In some cases, the cellulosic or lignocellulosic materials can beexposed to a particle beam in the presence of one or more additionalfluids (e.g., gases and/or liquids). Exposure of a material to aparticle beam in the presence of one or more additional fluids canincrease the efficiency of the treatment.

In some embodiments, the material is exposed to a particle beam in thepresence of a fluid such as air. Particles accelerated in any one ormore of the types of accelerators disclosed herein (or another type ofaccelerator) are coupled out of the accelerator via an output port(e.g., a thin membrane such as a metal foil), pass through a volume ofspace occupied by the fluid, and are then incident on the material. Inaddition to directly treating the material, some of the particlesgenerate additional chemical species by interacting with fluid particles(e.g., ions and/or radicals generated from various constituents of air,such as ozone and oxides of nitrogen). These generated chemical speciescan also interact with the material, and can act as initiators for avariety of different chemical bond-breaking reactions in the material.For example, any oxidant produced can oxidize the material, which canresult in molecular weight reduction.

In certain embodiments, additional fluids can be selectively introducedinto the path of a particle beam before the beam is incident on thematerial. As discussed above, reactions between the particles of thebeam and the particles of the introduced fluids can generate additionalchemical species, which react with the material and can assist infunctionalizing the material, and/or otherwise selectively alteringcertain properties of the material. The one or more additional fluidscan be directed into the path of the beam from a supply tube, forexample. The direction and flow rate of the fluid(s) that is/areintroduced can be selected according to a desired exposure rate and/ordirection to control the efficiency of the overall treatment, includingeffects that result from both particle-based treatment and effects thatare due to the interaction of dynamically generated species from theintroduced fluid with the material. In addition to air, exemplary fluidsthat can be introduced into the ion beam include oxygen, nitrogen, oneor more noble gases, one or more halogens, and hydrogen.

Cooling Irradiated Materials

During treatment of the materials discussed above with ionizingradiation, especially at high dose rates, such as at rates greater then0.15 Mrad per second, e.g., 0.25 Mrad/s, 0.35 Mrad/s, 0.5 Mrad/s, 0.75Mrad/s or even greater than 1 Mrad/sec, the materials can retainsignificant quantities of heat so that the temperature of the materialbecomes elevated. While higher temperatures can, in some embodiments, beadvantageous, e.g., when a faster reaction rate is desired, it isadvantageous to control the heating to retain control over the chemicalreactions initiated by the ionizing radiation, such as crosslinking,chain scission and/or grafting, e.g., to maintain process control.

For example, in one method, the material is irradiated at a firsttemperature with ionizing radiation, such as photons, electrons or ions(e.g., singularly or multiply charged cations or anions), for asufficient time and/or a sufficient dose to elevate the material to asecond temperature higher than the first temperature. The irradiatedmaterial is then cooled to a third temperature below the secondtemperature. If desired, the cooled material can be treated one or moretimes with radiation, e.g., with ionizing radiation. If desired, coolingcan be applied to the material after and/or during each radiationtreatment.

Cooling can in some cases include contacting the material with a fluid,such as a gas, at a temperature below the first or second temperature,such as gaseous nitrogen at or about 77 K. Even water, such as water ata temperature below nominal room temperature (e.g., 25 degrees Celsius)can be utilized in some implementations.

Types of Radiation

The radiation can be provided, e.g., by: 1) heavy charged particles,such as alpha particles; 2) electrons, produced, for example, in betadecay or electron beam accelerators; or 3) electromagnetic radiation,e.g., gamma rays, x-rays or ultraviolet rays. Different forms ofradiation ionize the biomass via particular interactions, as determinedby the energy of the radiation.

Heavy charged particles primarily ionize matter via Coulomb scattering;furthermore, these interactions produce energetic electrons that canfurther ionize matter. Alpha particles are identical to the nucleus of ahelium atom and are produced by alpha decay of various radioactivenuclei, such as isotopes of bismuth, polonium, astatine, radon,francium, radium, several actinides, such as actinium, thorium, uranium,neptunium, curium, californium, americium and plutonium.

Electrons interact via Coulomb scattering and bremssthrahlung radiationproduced by changes in the velocity of electrons. Electrons can beproduced by radioactive nuclei that undergo beta decay, such as isotopesof iodine, cesium, technetium and iridium. Alternatively, an electrongun can be used as an electron source via thermionic emission.

Electromagnetic radiation interacts via three processes: photoelectricabsorption, Compton scattering and pair production. The dominatinginteraction is determined by the energy of incident radiation and theatomic number of the material. The summation of interactionscontributing to the absorbed radiation in cellulosic material can beexpressed by the mass absorption coefficient.

Electromagnetic radiation is subclassified as gamma rays, x-rays,ultraviolet rays, infrared rays, microwaves or radio waves, depending onits wavelength.

For example, gamma radiation can be employed to irradiate the materials.Referring to FIGS. 2 and 3 (an enlarged view of region R), a gammairradiator 10 includes gamma radiation sources 408, e.g., ⁶⁰Co pellets,a working table 14 for holding the materials to be irradiated andstorage 16, e.g., made of a plurality iron plates, all of which arehoused in a concrete containment chamber (vault) 20 that includes a mazeentranceway 22 beyond a lead-lined door 26. Storage 16 defines aplurality of channels 30, e.g., sixteen or more channels, allowing thegamma radiation sources to pass through storage on their way proximatethe working table.

In operation, the sample to be irradiated is placed on a working table.The irradiator is configured to deliver the desired dose rate andmonitoring equipment is connected to an experimental block 31. Theoperator then leaves the containment chamber, passing through the mazeentranceway and through the lead-lined door. The operator mans a controlpanel 32, instructing a computer 33 to lift the radiation sources 12into working position using cylinder 36 attached to hydraulic pump 40.

Gamma radiation has the advantage of significant penetration depth intoa variety of materials in the sample. Sources of gamma rays includeradioactive nuclei, such as isotopes of cobalt, calcium, technicium,chromium, gallium, indium, iodine, iron, krypton, samarium, selenium,sodium, thalium and xenon.

Sources of x-rays include electron beam collision with metal targets,such as tungsten or molybdenum or alloys, or compact light sources, suchas those produced commercially by Lyncean Technologies, Inc., of PaloAlto, Calif.

Sources for ultraviolet radiation include deuterium or cadmium lamps.

Sources for infrared radiation include sapphire, zinc or selenide windowceramic lamps.

Sources for microwaves include klystrons, Slevin type RF sources or atombeam sources that employ hydrogen, oxygen or nitrogen gases.

In some embodiments, a beam of electrons is used as the radiationsource. A beam of electrons has the advantages of high dose rates (e.g.,1, 5, or even 10 MRad per second), high throughput, less containment andless confinement equipment. Electrons can also be more efficient atcausing chain scission. In addition, electrons having energies of 4-10MeV can have penetration depths of 5 to 30 mm or more, such as 40 mm.

Electron beams can be generated, e.g., by electrostatic generators,cascade generators, transformer generators, low energy accelerators witha scanning system, low energy accelerators with a linear cathode, linearaccelerators, and pulsed accelerators. Electrons as an ionizingradiation source can be useful, e.g., for relatively thin materials,e.g., less than 0.5 inch, e.g., less than 0.4 inch, 0.3 inch, 0.2 inch,or less than 0.1 inch. In some embodiments, the energy of each electronof the electron beam is from about 0.25 MeV to about 7.5 MeV (millionelectron volts), e.g., from about 0.5 MeV to about 5.0 MeV, or fromabout 0.7 MeV to about 2.0 MeV. Electron beam irradiation devices may beprocured commercially from Ion Beam Applications, Louvain-la-Neuve,Belgium or from Titan Corporation, San Diego, Calif. Typical electronenergies can be 1, 2, 4.5, 7.5, or 10 MeV. Typical electron beamirradiation device power can be 1, 5, 10, 20, 50, 100, 250, or 500 kW.Typical doses may take values of 1, 5, 10, 20, 50, 100, or 200 kGy.

Tradeoffs in considering electron beam irradiation device powerspecifications include operating costs, capital costs, depreciation anddevice footprint. Tradeoffs in considering exposure dose levels ofelectron beam irradiation would be energy costs and environment, safety,and health (ESH) concerns. Typically, generators are housed in a vault,e.g., of lead or concrete.

The electron beam irradiation device can produce either a fixed beam ora scanning beam. A scanning beam may be advantageous with large scansweep length and high scan speeds, as this would effectively replace alarge, fixed beam width. Further, available sweep widths of 0.5 m, 1 m,2 m or more are available.

In embodiments in which the irradiating is performed withelectromagnetic radiation, the electromagnetic radiation can have anenergy per photon (in electron volts) of, e.g., greater than 10² eV,e.g., greater than 10³, 10⁴, 10⁵, 10⁶ or even greater than 10⁷ eV. Insome embodiments, the electromagnetic radiation has energy per photon ofbetween 10⁴ and 10⁷, e.g., between 10⁵ and 10⁶ eV. The electromagneticradiation can have a frequency of, e.g., greater than 10¹⁶ hz, greaterthan 10¹⁷ hz, 10¹⁸, 10¹⁹, 10²⁰ or even greater than 10²¹ hz. In someembodiments, the electromagnetic radiation has a frequency of between10¹⁸ and 10²² Hz, e.g., between 10¹⁹ to 10²¹ Hz.

One type of accelerator that can be used to accelerate ions producedusing the sources discussed above is a Dynamitron® (available, forexample, from Radiation Dynamics Inc., now a unit of IBA,Louvain-la-Neuve, Belgium). A schematic diagram of a Dynamitron®accelerator 1500 is shown in FIG. 4. Accelerator 1500 includes aninjector 1510 (which includes an ion source) and an accelerating column1520 that includes a plurality of annular electrodes 1530. Injector 1510and column 1520 are housed within an enclosure 1540 that is evacuated bya vacuum pump 1600.

Injector 1510 produces a beam of ions 1580, and introduces beam 1580into accelerating column 1520. The annular electrodes 1530 aremaintained at different electric potentials, so that ions areaccelerated as they pass through gaps between the electrodes (e.g., theions are accelerated in the gaps, but not within the electrodes, wherethe electric potentials are uniform). As the ions travel from the top ofcolumn 1520 toward the bottom in FIG. 4, the average speed of the ionsincreases. The spacing between subsequent annular electrodes 1530typically increases, therefore, to accommodate the higher average ionspeed.

After the accelerated ions have traversed the length of column 1520, theaccelerated ion beam 1590 is coupled out of enclosure 1540 throughdelivery tube 1555. The length of delivery tube 1555 is selected topermit adequate shielding (e.g., concrete shielding) to be positionedadjacent to column 1520, isolating the column. After passing throughtube 1555, ion beam 1590 passes through scan magnet 1550. Scan magnet1550, which is controlled by an external logic unit (not shown), cansweep accelerated ion beam 1590 in controlled fashion across atwo-dimensional plane oriented perpendicular to a central axis of column1520. As shown in FIG. 4, ion beam 1590 passes through window 1560(e.g., a metal foil window or screen) and then is directed to impinge onselected regions of a sample 1570 by scan magnet 1550.

In some embodiments, the electric potentials applied to electrodes 1530are static potentials, generated, e.g., by DC potential sources. Incertain embodiments, some or all of the electric potentials applied toelectrodes 1530 are variable potentials generated by variable potentialsources. Suitable variable sources of large electric potentials includeamplified field sources, e.g. such as klystrons. Accordingly, dependingupon the nature of the potentials applied to electrodes 1530,accelerator 1500 can operate in either pulsed or continuous mode.

To achieve a selected accelerated ion energy at the output end of column1520, the length of column 1520 and the potentials applied to electrodes1530 are chosen based on considerations well-known in the art. However,it is notable that to reduce the length of column 1520, multiply-chargedions can be used in place of singly-charged ions. That is, theaccelerating effect of a selected electric potential difference betweentwo electrodes is greater for an ion bearing a charge of magnitude 2 ormore than for an ion bearing a charge of magnitude 1. Thus, an arbitraryion X²⁺ can be accelerated to final energy E over a shorter length thana corresponding arbitrary ion X⁺. Triply- and quadruply-charged ions(e.g., X³⁺ and X⁴⁺) can be accelerated to final energy E over evenshorter distances. Therefore, the length of column 1520 can besignificantly reduced when ion beam 1580 includes primarilymultiply-charged ion species.

To accelerate positively-charged ions, the potential differences betweenelectrodes 1530 of column 1520 are selected so that the direction ofincreasing field strength in FIG. 4 is downward (e.g., toward the bottomof column 1520). Conversely, when accelerator 1500 is used to acceleratenegatively-charged ions, the electric potential differences betweenelectrodes 1530 are reversed in column 1520, and the direction ofincreasing field strength in FIG. 4 is upward (e.g., toward the top ofcolumn 1520). Reconfiguring the electric potentials applied toelectrodes 1530 is a straightforward procedure, so that accelerator 1500can be converted relatively rapidly from accelerating positive ions toaccelerating negative ions, or vice versa. Similarly, accelerator 1500can be converted rapidly from accelerating singly-charged ions toaccelerating multiply-charged ions, and vice versa.

Doses

In some embodiments, irradiation is used to reduce molecular weight(with any radiation source or a combination of sources), in which caseirradiation can be performed until the material receives a dose of atleast 2.5 MRad, e.g., at least 5.0, 7.5, 10.0, 100, or 500 MRad. In someembodiments, the irradiating is performed until the material receives adose of between 3.0 MRad and 100 MRad, e.g., between 10 MRad and 100MRad or between 25 MRad and 75 MRad. If gamma radiation is used, thedose will generally be towards the higher end of these ranges, while ifelectron beam radiation is used, the dose may, in some embodiments, betowards the lower end. Dosage rates will also be towards the lower endfor some cellulosic materials which already have relatively lowmolecular weight, e.g. recycled paper.

In other embodiments, irradiation is used to increase molecular weight(with any radiation source or a combination of sources), in which caseirradiation can be performed until the material receives a dose of atleast 0.05 MRad, e.g., at least 0.1, 0.25, 1.0, 2.5, or 5.0 MRad. Insome embodiments, irradiating is performed until the material receives adose of between 0.1 and 2.5 MRad. Other suitable ranges include between0.25 MRad and 4.0 MRad, between 0.5 MRad and 3.0 MRad, and between 1.0MRad and 2.5 MRad.

Any of the doses discussed above will functionalize the material, withthe degree of functionalization generally being higher the higher thedose.

In some embodiments, the irradiating is performed at a dose rate ofbetween 5.0 and 1500.0 kilorads/hour, e.g., between 10.0 and 750.0kilorads/hour or between 50.0 and 350.0 kilorads/hours. When highthroughput is desired, e.g., in a high speed papermaking process,radiation can be applied at, e.g., 0.5 to 3.0 MRad/sec, or even faster,using cooling to avoid overheating the irradiated material.

In some embodiments in which coated paper is irradiated, the papercoating includes resin that is cross-linkable, e.g., diacrylate orpolyethylene. As such, the resin crosslinks as thecarbohydrate-containing material is irradiated to increase its molecularweight, which can provide a synergistic effect to optimize the scuffresistance and other surface properties of the paper. In theseembodiments, the dose of radiation is selected to be sufficiently highso as to increase the molecular weight of the cellulosic fibers, i.e.,at least about 0.25 to about 2.5 MRad, depending on the material, whilebeing sufficiently low so as to avoid deleteriously affecting the papercoating. The upper limit on the dose will vary depending on thecomposition of the coating, but in some embodiments the preferred doseis less than about 5 MRad.

In some embodiments, two or more radiation sources are used, such as twoor more ionizing radiations. For example, samples can be treated, in anyorder, with a beam of electrons, followed by gamma radiation and/or UVlight having wavelengths from about 100 nm to about 280 nm. In someembodiments, samples are treated with three ionizing radiation sources,such as a beam of electrons, gamma radiation, and energetic UV light.

Irradiating Devices

Various irradiating devices may be used in the methods disclosed herein,including field ionization sources, electrostatic ion separators, fieldionization generators, thermionic emission sources, microwave dischargeion sources, recirculating or static accelerators, dynamic linearaccelerators, van de Graaff accelerators, and folded tandemaccelerators. Such devices are disclosed, for example, in U.S.Provisional Application Ser. No. 61/073,665, the complete disclosure ofwhich is incorporated herein by reference.

Acoustic Energy

Radiation may be used in combination with acoustic energy, e.g., sonicor ultrasonic energy, to improve material throughput and/orcharacteristics, and/or to minimize energy usage. Suitable acousticenergy systems are described, for example, in U.S. ProvisionalApplication No. 61/049,407, the disclosure of which is incorporatedherein by reference.

Additives

Any of the many additives and coatings used with cellulosic andlignocellulosic materials, e.g., in the papermaking and textileindustries, can be added to or applied to the fibrous materials, papers,or any other materials and products described herein. Additives includefillers such as calcium carbonate, plastic pigments, graphite,wollastonite, mica, glass, fiber glass, silica, and talc; inorganicflame retardants such as alumina trihydrate or magnesium hydroxide;organic flame retardants such as chlorinated or brominated organiccompounds; carbon fibers; and metal fibers or powders (e.g., aluminum,stainless steel). These additives can reinforce, extend, or changeelectrical or mechanical properties, compatibility properties, or otherproperties. Other additives include starch, lignin, fragrances, couplingagents, antioxidants, opacifiers, heat stabilizers, colorants such asdyes and pigments, polymers, e.g., degradable polymers,photostabilizers, and biocides. Representative degradable polymersinclude polyhydroxy acids, e.g., polylactides, polyglycolides andcopolymers of lactic acid and glycolic acid, poly(hydroxybutyric acid),poly(hydroxyvaleric acid), poly[lactide-co-(ε-caprolactone)],poly[glycolide-co-(ε-caprolactone)], polycarbonates, poly(amino acids),poly(hydroxyalkanoate)s, polyanhydrides, polyorthoesters and blends ofthese polymers.

When additives are included, they can be present in amounts, calculatedon a dry weight basis, of from below about 1 percent to as high as about80 percent, based on total weight of the fibrous material. Moretypically, amounts range from between about 0.5 percent to about 50percent by weight, e.g., from about 0.5 percent to about 5 percent, 10percent, 20 percent, 30, percent or more, e.g., 40 percent.

Any additives described herein can be encapsulated, e.g., spray dried ormicroencapsulated, e.g., to protect the additives from heat or moistureduring handling.

Suitable coatings include any of the many coatings used in the paper andtextile industries to provide specific surface characteristics,including performance characteristics required for particular printingapplications, and in the case of textiles desired tactile properties,water repellency, flame retardancy, and the like.

Process Water

In the processes disclosed herein, whenever water is used in anyprocess, it may be grey water, e.g., municipal grey water, or blackwater. In some embodiments, the grey or black water is sterilized priorto use. Sterilization may be accomplished by any desired technique, forexample by irradiation, steam, or chemical sterilization.

EXAMPLES

The following examples are not intended to limit the inventions recitedin the claims.

Example 1 Methods of Determining Molecular Weight of Cellulosic andLignocellulosic Materials by Gel Permeation Chromatography

This example illustrates how molecular weight is determined for thematerials discussed herein. Cellulosic and lignocellulosic materials foranalysis were treated as follows:

A 1500 pound skid of virgin bleached white Kraft board having a bulkdensity of 30 lb/ft³ was obtained from International Paper. The materialwas folded flat, and then fed into a 3 hp Flinch Baugh shredder at arate of approximately 15 to 20 pounds per hour. The shredder wasequipped with two 12 inch rotary blades, two fixed blades and a 0.30inch discharge screen. The gap between the rotary and fixed blades wasadjusted to 0.10 inch. The output from the shredder resembled confetti(as above). The confetti-like material was fed to a Munson rotary knifecutter, Model SC30. The discharge screen had ⅛ inch openings. The gapbetween the rotary and fixed blades was set to approximately 0.020 inch.The rotary knife cutter sheared the confetti-like pieces across theknife-edges. The material resulting from the first shearing was fed backinto the same setup and the screen was replaced with a 1/16 inch screen.This material was sheared. The material resulting from the secondshearing was fed back into the same setup and the screen was replacedwith a 1/32 inch screen. This material was sheared. The resultingfibrous material had a BET surface area of 1.6897 m²/g+/−0.0155 m²/g, aporosity of 87.7163 percent and a bulk density (0.53 psia) of 0.1448g/mL. An average length of the fibers was 0.824 mm and an average widthof the fibers was 0.0262 mm, giving an average L/D of 32:1.

Sample materials presented in the following Tables 1 and 2 include Kraftpaper (P), wheat straw (WS), alfalfa (A), and switchgrass (SG). Thenumber “132” of the Sample ID refers to the particle size of thematerial after shearing through a 1/32 inch screen. The number after thedash refers to the dosage of radiation (MRad) and “US” refers toultrasonic treatment. For example, a sample ID “P132-10” refers to Kraftpaper that has been sheared to a particle size of 132 mesh and has beenirradiated with 10 MRad.

TABLE 1 Peak Average Molecular Weight of Irradiated Kraft Paper SampleDosage¹ Average MW ± Source Sample ID (MRad) Ultrasound² Std Dev. KraftPaper P132 0 No 32853 ± 10006 P132-10 10 ″  61398 ± 2468** P132-100 100″ 8444 ± 580  P132-181 181 ″ 6668 ± 77  P132-US 0 Yes 3095 ± 1013 **Lowdoses of radiation appear to increase the molecular weight of somematerials ¹Dosage Rate = 1 MRad/hour ²Treatment for 30 minutes with 20kHz ultrasound using a 1000 W horn under re-circulating conditions withthe material dispersed in water.

TABLE 2 Peak Average Molecular Weight of Irradiated Materials Dosage¹Average MW ± Sample ID Peak # (MRad) Ultrasound² Std Dev. WS132 1 0 No1407411 ± 175191 2 ″ ″ 39145 ± 3425 3 ″ ″ 2886 ± 177 WS132-10* 1 10 ″26040 ± 3240 WS132-100* 1 100 ″ 23620 ± 453  A132 1 0 ″ 1604886 ± 1517012 ″ ″ 37525 ± 3751 3 ″ ″ 2853 ± 490 A132-10* 1 10 ″ 50853 ± 1665 2 ″ ″2461 ± 17  A132-100* 1 100 ″ 38291 ± 2235 2 ″ ″ 2487 ± 15  SG132 1 0 ″1557360 ± 83693  2 ″ ″ 42594 ± 4414 3 ″ ″ 3268 ± 249 SG132-10* 1 10 ″60888 ± 9131 SG132-100* 1 100 ″ 22345 ± 3797 SG132-10- 1 10 Yes  86086 ±43518 US 2 ″ ″ 2247 ± 468 SG132-100- 1 100 ″  4696 ± 1465 US *Peakscoalesce after treatment **Low doses of radiation appear to increase themolecular weight of some materials ¹Dosage Rate = 1 MRad/hour ²Treatmentfor 30 minutes with 20 kHz ultrasound using a 1000 W horn underre-circulating conditions with the material dispersed in water.

Gel Permeation Chromatography (GPC) is used to determine the molecularweight distribution of polymers. During GPC analysis, a solution of thepolymer sample is passed through a column packed with a porous geltrapping small molecules. The sample is separated based on molecularsize with larger molecules eluting sooner than smaller molecules. Theretention time of each component is most often detected by refractiveindex (RI), evaporative light scattering (ELS), or ultraviolet (UV) andcompared to a calibration curve. The resulting data is then used tocalculate the molecular weight distribution for the sample.

A distribution of molecular weights rather than a unique molecularweight is used to characterize synthetic polymers. To characterize thisdistribution, statistical averages are utilized. The most common ofthese averages are the “number average molecular weight” (M_(n)) and the“weight average molecular weight” (M_(w)). Methods of calculating thesevalues are described in the art, e.g., in Example 9 of WO 2008/073186.

The polydispersity index or PI is defined as the ratio of M_(n)/M_(w).The larger the PI, the broader or more disperse the distribution. Thelowest value that a PI can be is 1. This represents a monodispersesample; that is, a polymer with all of the molecules in the distributionbeing the same molecular weight.

The peak molecular weight value (M_(P)) is another descriptor defined asthe mode of the molecular weight distribution. It signifies themolecular weight that is most abundant in the distribution. This valuealso gives insight to the molecular weight distribution.

Most GPC measurements are made relative to a different polymer standard.The accuracy of the results depends on how closely the characteristicsof the polymer being analyzed match those of the standard used. Theexpected error in reproducibility between different series ofdeterminations, calibrated separately, is around 5-10% and ischaracteristic to the limited precision of GPC determinations.Therefore, GPC results are most useful when a comparison between themolecular weight distributions of different samples is made during thesame series of determinations.

The lignocellulosic samples required sample preparation prior to GPCanalysis. First, a saturated solution (8.4% by weight) of lithiumchloride (LiCl) was prepared in dimethyl acetamide (DMAc). Approximately100 mg of the sample was added to approximately 10 g of a freshlyprepared saturated LiCl/DMAc solution, and the mixture was heated toapproximately 150° C.-170° C. with stirring for 1 hour. The resultingsolutions were generally light- to dark-yellow in color. The temperatureof the solutions were decreased to approximately 100° C. and heated foran additional 2 hours. The temperature of the solutions was thendecreased to approximately 50° C. and the sample solutions were thenheated for approximately 48 to 60 hours. Of note, samples irradiated at100 MRad were more easily solubilized as compared to their untreatedcounterpart. Additionally, the sheared samples (denoted by the number132) had slightly lower average molecular weights as compared with uncutsamples.

The resulting sample solutions were diluted 1:1 using DMAc as solventand were filtered through a 0.45 μm PTFE filter. The filtered samplesolutions were then analyzed by GPC. The peak average molecular weights(M_(P)) of the samples, as determined by Gel Permeation Chromatography(GPC), are summarized in Tables 1 and 2, above. Each sample was preparedin duplicate and each preparation of the sample was analyzed induplicate (two injections) for a total of four injections per sample.The EasiCal® polystyrene standards PSIA and PSIB were used to generate acalibration curve for the molecular weight scale from about 580 to7,500,00 Daltons. GPC analysis conditions are recited in Table 3, below.

TABLE 3 GPC Analysis Conditions Instrument: Waters Alliance GPC 2000Plgel 10μ Mixed-B Columns (3): S/N's: 10M-MB-148-83; 10M-MB-148-84;10M-MB-174-129 Mobile Phase (solvent): 0.5% LiCl in DMAc (1.0 mL/min.)Column/Detector Temperature: 70° C. Injector Temperature: 70° C. SampleLoop Size: 323.5 μL

Example 2 Electron Beam Processing Cardboard Samples

Brown cardboard samples 0.050 inches thick were treated with a beam ofelectrons using a vaulted Rhodotron® TT200 continuous wave acceleratordelivering 5 MeV electrons at 80 kW output power. Table 4 describes thenominal parameters for the TT200. Table 5 reports the nominal doses (inMRad) and actual doses (in kgy) delivered to the samples.

TABLE 4 Rhodotron ® TT 200 Parameters Beam Beam Produced: Acceleratedelectrons Beam energy: Nominal (maximum): 10 MeV (+0 keV-250 keV Energydispersion at 10 Mev: Full width half maximum (FWHM) 300 keV Beam powerat 10 MeV: Guaranteed Operating Range 1 to 80 kW Power ConsumptionStand-by condition (vacuum and cooling ON):  <15 kW At 50 kW beam power:<210 kW At 80 kW beam power: <260 kW RF System Frequency: 107.5 ± 1 MHzTetrode type: Thomson TH781 Scanning Horn Nominal Scanning Length(measured at 25-35 120 cm cm from window): Scanning Range: From 30% to100% of Nominal Scanning Length Nominal Scanning Frequency (at max. 100Hz ± 5% scanning length): Scanning Uniformity (across 90% of Nominal ±5%Scanning Length)

TABLE 5 Dosages Delivered to Samples Total Dosage (MRad) (NumberAssociated with Sample ID Delivered Dose (kgy)¹ 1 9.9 3 29.0 5 50.4 769.2 10 100.0 15 150.3 20 198.3 30 330.9 50 529.0 70 695.9 100 993.6¹For example, 9.9 kgy was delivered in 11 seconds at a beam current of 5mA and a line speed of 12.9 feet/minute. Cool time between 1 MRadtreatments was about 2 minutes.

The cardboard samples treated below 7 MRad were stiffer to the touchthan untreated controls, but otherwise appeared visibly identical to thecontrols. Samples treated at about 10 MRad were of comparable stiffnessto the controls to the touch, while those treated with higher doses weremore flexible under manipulation. Extensive material degradation wasvisibly apparent for samples treated above 50 Mrad.

Example 3 Fourier Transform Infrared (FT-IR) Spectrum of Irradiated andUnirradiated Kraft Paper

FT-IR analysis was performed on a Nicolet/Impact 400. The resultsindicate that samples P132, P132-10, P132-100, P-1e, P-5e, P-10e, P-30e,P-70e, and P-100e are consistent with a cellulose-based material.

FIG. 5 is an infrared spectrum of Kraft board paper sheared according toExample 4, while FIG. 6 is an infrared spectrum of the Kraft paper ofFIG. 5 after irradiation with 100 Mrad of gamma radiation. Theirradiated sample shows an additional peak in region A (centered about1730 cm⁻¹) that is not found in the un-irradiated material. Of note, anincrease in the amount of a carbonyl absorption at ˜1650 cm⁻¹ wasdetected when going from P132 to P132-10 to P132-100. Similar resultswere observed for the samples P-1e, P-5e, P-10e, P-30e, P-70e, andP-100e.

Example 4 Proton and Carbon-13 Nuclear Magnetic Resonance (¹H-NMR and¹³C-NMR) Spectra of Irradiated and Unirradiated Kraft Paper SamplePreparation

The samples P132, P132-10, P132-100, P-1e, P-5e, P-10e, P-30e, P-70e,and P-100e were prepared for analysis by dissolution with DMSO-d₆ with2% tetrabutyl ammonium fluoride trihydrate. The samples that hadundergone lower levels of irradiation were significantly less solublethan the samples with higher irradiation. Unirradiated samples formed agel in this solvent mixture, but heating to 60° C. resolved the peaks inthe NMR spectra. The samples having undergone higher levels ofirradiation were soluble at a concentration of 10% wt/wt.

Analysis

¹H-NMR spectra of the samples at 15 mg/mL showed a distinct very broadresonance peak centered at 16 ppm (FIGS. 6A-6J). This peak ischaracteristic of an exchangeable —OH proton for an enol and wasconfirmed by a “D₂O shake.” Model compounds (acetylacetone, glucuronicacid, and keto-gulonic acid) were analyzed and made a convincing casethat this peak was indeed an exchangeable enol proton. This proposedenol peak was very sensitive to concentration effects, and we wereunable to conclude whether this resonance was due to an enol or possiblya carboxylic acid.

The carboxylic acid proton resonances of the model compounds weresimilar to what was observed for the treated cellulose samples. Thesemodel compounds were shifted up field to ˜5-6 ppm. Preparation of P-100eat higher concentrations (˜10% wt/wt) led to the dramatic down fieldshifting to where the carboxylic acid resonances of the model compoundswere found (˜6 ppm) (FIG. 6N). These results lead to the conclusion thatthis resonance is unreliable for characterizing this functional group,however the data suggests that the number of exchangeable hydrogensincreases with increasing irradiation of the sample. Also, no vinylprotons were detected.

The ¹³C NMR spectra of the samples confirm the presence of a carbonyl ofa carboxylic acid or a carboxylic acid derivative. This new peak (at 168ppm) is not present in the untreated samples (FIG. 6K). A ¹³C NMRspectrum with a long delay allowed the quantitation of the signal forP-100e (FIGS. 6L-6M). Comparison of the integration of the carbonylresonance to the resonances at approximately 100 ppm (the C1 signals)suggests that the ratio of the carbonyl carbon to C1 is 1:13.8 orroughly 1 carbonyl for every 14 glucose units. The chemical shift at 100ppm correlates well with glucuronic acid.

Titration

Samples P-100e and P132-100 (1 g) were suspended in deionized water (25mL). The indicator alizarin yellow was added to each sample withstirring. P-100e was more difficult to wet. Both samples were titratedwith a solution of 0.2M NaOH. The end point was very subtle and wasconfirmed by using pH paper. The starting pH of the samples was ˜4 forboth samples. P132-100 required 0.4 milliequivalents of hydroxide, whichgives a molecular weight for the carboxylic acid of 2500 amu. If 180 amuis used for a monomer, this suggests there is one carboxylic acid groupfor 13.9 monomer units. Likewise, P-100e required 3.2 milliequivalentsof hydroxide, which calculates to be one carboxylic acid group for every17.4 monomer units.

Conclusions

The C-6 carbon of cellulose appears to be oxidized to the carboxylicacid (a glucuronic acid derivative) in this oxidation is surprisinglyspecific. This oxidation is in agreement with the IR band that growswith irradiation at ˜1740 cm⁻¹, which corresponds to an aliphaticcarboxylic acid. The titration results are in agreement with thequantitative ¹³C NMR. The increased solubility of the sample with thehigher levels of irradiation correlates well with the increasing numberof carboxylic acid protons. A proposed mechanism for the degradation of“C-6 oxidized cellulose” is provided below in Scheme 1.

Other Embodiments

It is to be understood that while the invention has been described inconjunction with the detailed description thereof, the foregoingdescription is intended to illustrate and not limit the scope of theinvention, which is defined by the scope of the appended claims. Otheraspects, advantages, and modifications are within the scope of thefollowing claims.

1. A method comprising: irradiating a lignocellulosic or cellulosicmaterial to provide an irradiated lignocellulosic or cellulosic materialhaving a larger number of carboxylic acid groups than the cellulosic orlignocellulosic material from which the irradiated material wasobtained.
 2. The method of claim 1 wherein the treated material furthercomprises functional groups selected from the group consisting ofaldehyde groups, nitroso groups, nitrile groups, nitro groups, ketonegroups, amino groups, alkyl amino groups, alkyl groups, chloroalkylgroups, chlorofluoroalkyl groups, and enol groups.
 3. The method ofclaim 1 wherein the naturally occurring cellulosic or lignocellulosicfibrous material is selected from the group consisting of wood, paper,and textile fibers.
 4. The method of claim 1 wherein the lignocellulosicor cellulosic material comprises a fibrous material.
 5. The method ofclaim 1 comprising a plurality of saccharide units arranged in amolecular chain, wherein from about 1 out of every 2 to about 1 out ofevery 250 saccharide units comprises a carboxylic acid group, or anester or salt thereof, wherein the number of carboxylic acid groups isdetermined by titration.
 6. The method of claim 5, wherein the materialincludes a plurality of said molecular chains.
 7. The method of claim 6,wherein each chain comprises hemicellulose or cellulose.
 8. The methodof claim 6, wherein from about 1 out of every 10 to about 1 out of every1000 saccharide units of each chain comprises a nitroso, nitro, ornitrile group.
 9. The method of claim 6, wherein from about 1 out ofevery 35 to about 1 out of every 750 saccharide units of each chaincomprises a nitroso, nitro, or nitrile group.
 10. The method of claim 5,wherein from about 1 out of every 5 to about 1 out of every 250saccharide units of each chain comprises a carboxylic acid group, or anester or salt thereof.
 11. The method of claim 5, wherein from about 1out of every 8 to about 1 out of every 100 saccharide units of eachchain comprises a carboxylic acid group, or an ester or salt thereof.12. The method of claim 5, wherein from about 1 out of every 10 to about1 out of every 50 saccharide units of each chain comprise a carboxylicacid group, or an ester or salt thereof.
 13. The method of claim 5,wherein the saccharide units comprise 5 or 6 carbon saccharide units.14. The method of claim 5, wherein each chain has between about 10 andabout 200 saccharide units, e.g., between about 10 and about 100 orbetween about 10 and about
 50. 15. The method of claim 5, wherein theaverage molecular weight of the material relative to PEG standards isfrom about 1,000 to about 1,000,000, wherein the molecular weight isdetermined using GPC, utilizing a saturated solution (8.4% by weight) oflithium chloride (LiCl) in dimethyl acetamide (DMAc) as the mobilephase.
 16. The method of claim 5, wherein from about 1 out of every 5 toabout 1 out of every 1500 saccharide units comprises a nitroso, nitro,or nitrile group.
 17. The method of claim 5, wherein the irradiatedmaterial comprises a mixture of nitrile groups and carboxylic acidgroups.
 18. A method comprising: surface treating with a coating or adye a cellulosic or lignocellulosic material that has been irradiated tofunctionalize the material with carboxylic acid groups not present in anaturally occurring cellulosic or lignocellulosic material from whichthe irradiated material was obtained.
 19. A method comprising: graftinga material onto grafting sites of a cellulosic or lignocellulosicmaterial that has been irradiated to provide a functionalized cellulosicmaterial having a plurality of grafting sites.
 20. The method of claim19 wherein the material comprises a reactive dye.
 21. A materialproduced by irradiating a lignocellulosic or cellulosic material toprovide an irradiated lignocellulosic or cellulosic material having alarger number of carboxylic acid groups than the cellulosic orlignocellulosic material from which the irradiated material wasobtained.